Frequently Asked Questions

Cem-Rock® is a family of magnesium oxide cement boards designed to replace plywood, OSB, fiber cement board and interior and exterior gypsum based sheet building products. 

Cem-Rock® is made of Magnesium Oxide (MgO). 

Magnesium Oxide (MgO) is a naturally occurring inorganic mineral that is mined from the earth much like Portland cement. 

Yes, Cem-Rock® can be used internally or externally. 

Cem-Rock® is most commonly used as exterior sheathing, interior wallboard, subflooring, ceilings, roof decking, fire-resistant wall and subfloor assemblies and tile backerboard. 

Cem-Rock® is available in 1200, 2400, 2700 and 3050mm lengths and 1200mm wide sheets. Other sizes are available by special order. 

Cem-Rock® and Cem-Rock® eXtreme are available in 6, 10, 12 and 15mm. Cem-Rock® FLOOR is available in 18 and 20mm. Other thicknesses are available by special order. 

Cem-Rock® is installed in a similar fashion to gypsum board, plywood, or OSB. 

Cem-Rock® can be nailed or screwed. 

Cem-Rock® is completely inorganic, does not rot, mold or feed mildew and has a 0/0/0 mold rating. 

No, Cem-Rock® is non-combustible and is Class A1 fire rated, with a 0 flame spread and 0 smoke
developed rating. No other plywood, OSB or gypsum based product can claim this.

No. A sheet of Cem-Rock® weights approx. 30kg and Cem-Rock® eXtreme weights approx. 37kg

Yes. Cem-Rock® is completely non-toxic. It is manufactured from 100% natural inputs and does not off-gas. It is exceptionally good for Asthma or chemically sensitive people.

Cem-Rock® can be scored and snapped like gypsum board, or you can use a circular saw. 

Yes, Cem-Rock® can be cut with a utility knife using score and snap method and also, dust generated when cut with a circular saw is non-carcinogenic. Cem-Rock® does not contain known toxins such as formaldehyde, crystalline silica or fly ash. 

Yes, Cem-Rock® carries all required certification. 

Nothing. It dries out and is unaffected by exposure to water. 

Cem-Rock® is impervious to water, both fresh and salt. Being cementitious, it does however absorb some water. 

Yes, Cem-Rock® is completely resistant to all wood boring insects. 

Yes. Cem-Rock® is one of the most dimensionally stable sheet building materials on the market. 

Cem-Rock® should be used wherever there is a need for a fireproof, mold proof, insect proof, waterproof and high impact alternative to gypsum board, plywood, OSB or fiber cement board. 

Stainless steel, yellow zinc coated or rust proof coated screws for fastening into steel framing or wood framing are recommended. Traditional (black) gypsum screws are not recommended. 

No, pre-drilling is not necessary. 

When using Cem-Rock® eXtreme, you can hang practically anything with no additional blocking needed.
(See Product Data Sheet for maximum fastener capacities). When using Cem-Rock®, blocking or plasterboard dowels might be required, depending on what is being fixed.